How Heterogeneous Pore Scale Distributions of Wettability Affect Infiltration into Porous Media

Wettability is an important parameter that significantly determines hydrology in porous media, and it especially controls the flow of water across the rhizosphere—the soil-plant interface. However, the influence of spatially heterogeneous distributions on the soil particles surfaces is scarcely known. Therefore, this study investigates the influence of spatially heterogeneous wettability distributions on infiltration into porous media. For this purpose, we utilize a two-phase flow model based on Lattice-Boltzmann to numerically simulate the infiltration in porous media with a simplified geometry and for various selected heterogeneous wettability coatings. Additionally, we simulated the rewetting of the dry rhizosphere of a sandy soil where dry hydrophobic mucilage depositions on the particle surface are represented via a locally increased contact angle. In particular, we can show that hydraulic dynamics and water repellency are determined by the specific location of wettability patterns within the pore space. When present at certain locations, tiny hydrophobic depositions can cause water repellency in an otherwise well-wettable soil. In this case, averaged, effective contact angle parameterizations such as the Cassie equation are unsuitable. At critical conditions, when the rhizosphere limits root water uptake, consideration of the specific microscale locations of exudate depositions may improve models of root water uptake

Optimasi Desain Konstruksi Sel Dan Sistem Injeksi Cairan Pada Sensor Qcm (Quartz Crystal Microbalance)

Sensor QCM merupakan salah satu sensor massa ultra sensitif, yang banyak diaplikasikan sebagai biosensor. Dalam aplikasinya sebagai biosensor, teknik immobilisasi digunakan untuk pendeteksian dan pengamatan reasksi antar biomolekul. Konstruksi sel atau sel reaksi dan sistem injeksi cairan sample memiliki peranan penting ketika proses immobilisasi pada sensor QCM. Telah banyak dilakukan penelitian tentang perancangan konstruksi sel dan efek laju alir carian sample terhadap frekuensi resonansi dari sensor QCM. Pada penelitian sebelumnya, telah diketahui bahwa efek laju alir dari sistem injeksi syringe pump berpengaruh pada respon frekuensi dari sensor QCM, semakin cepat laju alir cairan sample akan menimbulkan sinyal spike atau noise pada respon frekuensi dari sensor QCM. Pada penelitian ini dilakukan optimasi desain pada konstruksi sel dan sistem injeksi cairan sample untuk menghilangkan efek sinyal spike atau noise pada proses immobilisasi. Optimalisasi konstruksi sel dikakukan dengan melakukan treatment plasma oksidasi pada permukaan konstruksi sel dengan variasi durasi treatment yaitu 600, 1200 dan 1800 second. Optimasi pada sistem injeksi dilakukan dengan mengatur kecepatan laju alir. Didapatkan variasi kecepatan laju alir yaitu 0.7 sampai 6.3 L / second. Dengan melakukan optimalisasi pada konstruksi sel dan sistem injeksi cairan sample, sinyal spike atau noise ketika proses immobilisasi berhasil dihilangkan

A review of hydrogen/rock/brine interaction: Implications for hydrogen geo-storage

Hydrogen (H2) is currently considered a clean fuel to decrease anthropogenic greenhouse gas emissions and will play a vital role in climate change mitigation. Nevertheless, one of the primary challenges of achieving a complete H2 economy is the large-scale storage of H2, which is unsafe on the surface because H2 is highly compressible, volatile, and flammable. Hydrogen storage in geological formations could be a potential solution to this problem because of the abundance of such formations and their high storage capacities. Wettability plays a critical role in the displacement of formation water and determines the containment safety, storage capacity, and amount of trapped H2 (or recovery factor). However, no comprehensive review article has been published explaining H2 wettability in geological conditions. Therefore, this review focuses on the influence of various parameters, such as salinity, temperature, pressure, surface roughness, and formation type, on wettability and, consequently, H2 storage. Significant gaps exist in the literature on understanding the effect of organic material on H2 storage capacity. Thus, this review summarizes recent advances in rock/H2/brine systems containing organic material in various geological reservoirs. The paper also presents influential parameters affecting H2 storage capacity and containment safety, including liquid–gas interfacial tension, rock–fluid interfacial tension, and adsorption. The paper aims to provide the scientific community with an expert opinion to understand the challenges of H2 storage and identify storage solutions. In addition, the essential differences between underground H2 storage (UHS), natural gas storage, and carbon dioxide geological storage are discussed, and the direction of future research is presented. Therefore, this review promotes thorough knowledge of UHS, provides guidance on operating large-scale UHS projects, encourages climate engineers to focus more on UHS research, and provides an overview of advanced technology. This review also inspires researchers in the field of climate change to give more credit to UHS studies

Development of a lattice Boltzmann model to investigate the interaction mechanism of surface acoustic wave on a sessile droplet

This study focuses on the development of a three dimensional numerical model, based on the lattice Boltzmann method (LBM), for two-phase fluid flow dynamics employing a multiple-relaxation-time (MRT) pseudopotential scheme. The numerical model is applied in the investigation of acoustic interactions with microscale sessile droplets (1- 10 µl), under surface acoustic wave (SAW) excitation, through the introduction of additonal forcing terms in the LBM scheme. In the study, a range of resonant frequencies (61.7 - 250.1 MHz) are studied and quantatively compared to existing studies and experimental findings to verify the proposed model. The modelling predictions on the roles of forces (SAW, interfacial tension, inertia and viscosity) on the dynamics of mixing, pumping and jetting of a droplet are in good agreement with observations and experimental data. Further examination of the model, through parameter study, identified that the relaxation parameters considered free to tune in the MRT, play an important role in model stability, providing large reductions in spurious velocities, in both the liquid and gas phases, when the values are specified correctly. It has also been discovered that employing a dynamic contact angle hysteresis model increased the adhesion between the liquid droplet and the substrate, improving the agreement with experimental findings by up to 20%. Lastly, an investigation of various equation of state implementations revealed some fascinating differences in droplet dynamics and behaviours, owing primarily to the physical underpinning of which each is based upon. The developed model is successfully applied in the examination of various scenarios including SAW-droplet interactions on an inclined slope, droplet impact on flat (horizontal) and inclined surfaces with and without SAW interactions, and dual SAW interactions on a droplet at several configurations. The findings indicate the importance of applied SAW power, especially in inclined slope scenarios, to overcome the inertia and gravitational forces which act to counteract the droplet motion initiated by the acoustic wave direction of travel. Furthermore, a new multi-component multi-phase multi-pseudopotential (MCMP MPI) LB model is proposed. The study details initial model development and verification for classical benchmark cases, comparing to both the single-component (SCMP MPI) and publicised data. Similar to its SCMP MPI counterpart, the model displays excellent stability, even at high density ratios, and thermodynamic consistency. Comparison to the SCMP MPI model reveals lower spurious velocities are generated in the proposed MCMP model, approximately one order of magnitude lower. Close inspection of the interaction force implementation shows they are analogous whilst similar surface tension values are presented for both models. The proposed scheme signifies a new class of MPI model capable of simulating realistic fluid compositions for use in applications of scientific and engineering interest